In manufacturing luminaire reflectors on a mass-production basis, it is highly desirable that the amount of material consumed and the required tooling and labor be held to a minimum. In attempting to achieve such goals, it is a common practice to stamp from a sheet of metal a blank that can be bent into a trough-shaped form constituting the body of the reflector and integral end walls at opposite ends of the body constituting the end panels of the reflector. In prior uses of such a method, the blank cut from the metal sheet comprises two primary portions, each in the general form of a trapezoid having major and minor bases and side edges extending between the ends of the bases, the two trapezoidal primary portions being located with their minor bases aligned but spaced apart and joined by a junction portion having side edges extending between the ends of minor bases. Typical forms of this prior blank have further comprised, at each side of the junction portion, a secondary portion in the general form of a trapezoid having its minor base joined to the associated side edge of said junction portion. This blank is formed into a trough-shaped reflector by bending the blank at the minor bases of the trapezoidal portions so that the two primary portions form the body of the reflector and the two secondary portions form the end walls of the reflector.
A disadvantage of this prior method is that a blank of the described configuration requires a starting sheet of unduly large area.